1. Field of the Invention
The present invention generally relates to a fuel cell apparatus, in particular, to a flow channel plate adapted to a fuel cell apparatus.
2. Description of Related Art
Fuel cell is a next-generation power source for it has such advantages as high efficiency, low noise, and no pollution etc. Fuel cells are categorized into many different types, and the most common ones are proton exchange membrane fuel cell (PEMFC) and direct methanol fuel cell (DMFC). For example, the fuel cell module in a DMFC includes a proton exchange membrane and a cathode and an anode disposed at two sides of the proton exchange membrane.
A DMFC uses methanol-water solution as its fuel, and the chemical reaction equation thereof is:Anode: CH3OH+H2O→CO2+6H++6e−Cathode: 3/2O2+6H++6e−→3H2OOverall reaction: CH3OH+H2O+3/2O2→CO2+3H2O
Referring to FIG. 1, a conventional fuel cell apparatus 100 includes two fuel cell modules 110 and a cathode flow channel plate 120. The cathode flow channel plate 120, as shown in FIG. 2A, is disposed between the two fuel cell modules 110. The cathode flow channel plate 120 transmits the gas required by the cathodic reaction. Conventionally, a fan (not shown) is used for supplying the gas into the cathode flow channel plate 120.
Each of the fuel cell modules 110 includes two membrane electrode assemblies (MEAs) 112 and an anode flow channel plate 114. The anode flow channel plate 114 is disposed between the two MEAs 112. The anode flow channel plate 114, as shown in FIG. 2B, transmits the fuel required by the anodic reaction. Besides, each of the MEA 112 includes a proton exchange membrane 112a and an anode 112b and a cathode 112c disposed at two sides of the proton exchange membrane 112a, and the anode 112b of each of the MEAs 112 is adjacent to the anode flow channel plate 114. An anode current collector 116 is disposed at one side of each of the anodes 112b, and a cathode current collector 118 is disposed at one side of each of the cathodes 112c. 
Conventionally, the methods for fabricating the anode flow channel plate 114 and the cathode flow channel plate 120 includes plastic injection molding and plastic die-casting. In plastic injection molding, the thickness D1 of the thinnest parts of the anode flow channel plate 114 and the cathode flow channel plate 120 is about 0.8 mm. In plastic die-casting, the thickness D1 of the thinnest parts of the anode flow channel plate 114 and the cathode flow channel plate 120 is about 0.25 mm. In addition, the intensity of the anode flow channel plate 114 and the cathode flow channel plate 120 fabricated through plastic die-casting is lower than the intensity of the anode flow channel plate 114 and the cathode flow channel plate 120 fabricated through plastic injection molding.
The MEAs 112 have better reaction efficiency with certain compression (usually at about 30%), thus, appropriate pressure has to be supplied to the MEAs 112, and accordingly, the anode flow channel plate 114 and the cathode flow channel plate 116 have to have high intensities so that they are not damaged by the pressure. Accordingly, the anode flow channel plate 114 and the cathode flow channel plate 120 are usually fabricated through plastic injection molding in conventional technique.
However, since the design of the fuel cell apparatus 100 is going towards slimness, the thicknesses D2 and D3 of the cathode flow channel plate 120 and the anode flow channel plate 114 have to be reduced. With a fuel cell apparatus 100 used in a CD-ROM slot of a notebook PC as example, since the thickness of the CD-ROM slot is about 12.7 mm, the thickness D2 of the cathode flow channel plate 120 can be at most 1.4 mm. If the cathode flow channel plate 120 is fabricated through plastic injection molding, the thickness D1 of the thinnest part of the cathode flow channel plate 120 is 0.8 mm, therefore the maximum height H of the flow channels is only about 0.6 mm, which causes large resistance to the gas flow and accordingly reduces the reaction efficiency of the fuel cell apparatus 100. Besides, if a large fan with high power is used in order to improve the reaction efficiency of the fuel cell apparatus 100, the fan takes up too much space and consumes more energy.
Similarly, the reaction efficiency of the fuel cell apparatus 100 is reduced if the anode flow channel plate 114 is fabricated through plastic injection molding.